Police say two 12-year-old girls in Waukesha, Wis., are suspected of planning to kill their friend for months before allegedly one held her down and the other stabbed her on Saturday. (Reuters)

The prosecutor asked: “Isn’t that the worst kind of killer, the cold-blooded killer?”

“Most of the time in a crime like this, with such violence like this, there’s spur of the moment, there’s the heat of passion,” Waukesha County District Attorney Brad Schimel told reporters, describing the weekend’s slumber party stabbing. “It’s troubling when a person lashes out in anger. It’s more troubling when they lash out in cold blood.”

He was talking about a months-long murder plot involving three 12-year-old girls — two of them the alleged attackers and one of them the victim, who had 19 stab wounds.

One of the 12-year-old suspects told police the two girls decided to kill their friend to honor a mythological character they read about online, the criminal complaint stated.

So, after a slumber party, the two took their friend into a wooded park in southeastern Wisconsin and distracted her with a game of hide-and-seek. One girl told the other, “go ballistic, go crazy,” the complaint said, and they allegedly stabbed the friend 19 times.

One jab missed a major artery near her heart by a millimeter, doctors told police. The victim, who goes to school with the other two girls, was in stable condition Monday.

The two girls were charged as adults with first-degree attempted homicide Monday in Waukesha County Circuit Court, the Associated Press reported. If convicted, each faces up to 60 years in prison. A court commissioner set bail at $500,000 cash each.

Rescue workers take a stabbing victim to an ambulance in Waukesha, Wis., on May 31, 2014. (Abe Van Dyke/AP)

The Washington Post is not naming them because at least one of their attorneys reportedly plans to try to move her case to juvenile court, where records are private.

If either of the girls is moved to and convicted in juvenile court, she could be held at most until she is 25, Schimel told the Milwaukee Journal Sentinel.

“It’s extremely disturbing as a parent and as chief of police,” Waukesha Police Chief Russell Jack told reporters at a news conference before the court appearances.

The girls’ attorneys did not immediately return calls seeking comment early Tuesday.

The girls invited their friend to a slumber party on Friday evening, according to news reports of the allegations. They planned to kill her during the night so they wouldn’t have to look into her eyes, one girl told police. They would duct tape her mouth, stab her in the neck and pull the covers over her to make it appear she was sleeping — and then run away, the Journal Sentinel reported. But later that night their plans changed.

The girls allegedly decided to kill her in a park bathroom on Saturday morning. One girl told police she knew of a drain in the floor for the blood to go down. But once in the bathroom, one girl allegedly had a “nervous breakdown.” The other suggested a game.

During hide-and-seek, one girl reportedly tackled the victim and started stabbing. The Journal Sentinel reported that the victim screamed: “I hate you. I trusted you.”

One girl told the victim they were going to get help — but they weren’t, the paper said.

After they left, the victim crawled out of the woods and onto a road, where a bicyclist found her, CNN reported. The complaint states the victim said: “Please help me. I’ve been stabbed.” She could only answer questions by saying “yes” or “no.”

One of the girls told a detective they were trying to become “proxies” of Slender Man, a mythological demon-like creature they read about on creepypasta.wikia.com, a Web site about horror stories and legends. One of the girls told police the character is the “leader” of Creepypasta, and in the hierarchy of that world, one must kill to prove dedication, the Journal Sentinel reported. After the slaying, the girls planned to run away to the demon’s mansion in the Nicolet National Forest in Wisconsin, the complaint said.

One girl said she sees him in her dreams. She said he can read her mind and teleport.

Creepypasta comes from the Internet slang term copypasta, a block of text that is copied and pasted on numerous sites. Its stories often include anecdotes, rituals or lost episodes of TV shows, USA Today reported. Rituals include a “list of instructions for the reader, claiming that if they go to a certain place at a certain time, and perform specific actions, something remarkable and/or horrifying will happen,” the site states.

Schimel stressed that the two suspects are innocent until proven guilty, but he told the Journal Sentinel he has never encountered allegations like this as a prosecutor.

Lindsey Bever is a national news reporter for The Washington Post. She writes for the Morning Mix news blog. Tweet her: @lindseybever

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